Dot 4 Brake Fluid

[MichiganBob]

Good Afternoon.

 

I'm progressing through my 12K maintenance and now ready for brake bleed and replenish. I know about the many opinions about oil and tires but when it comes to brake fluid, is there some fancy stuff I should be buying or is Dot 4 Dot 4.

 

Many thanks.

[strataj]

I buy my DOT 4 at Walmart - Pestone . 

[Bernie]

I believe the new DOT 4 LV brake fluid is the recommended brake fluid for the newer BMW bikes, (2014 and newer).

That is @Boxflyer used during my recent brake flush @ The UnRally 2022.

You should be able to find it at a local auto parts store. 

[dirtrider]

1 hour ago, MichiganBob said:

Good Afternoon.

 

I'm progressing through my 12K maintenance and now ready for brake bleed and replenish. I know about the many opinions about oil and tires but when it comes to brake fluid, is there some fancy stuff I should be buying or is Dot 4 Dot 4.

 

Many thanks.

Afternoon MichiganBob

 

As Bernie said, you really want to use Low Viscosity Dot 4. The LV (Low Viscosity) is needed if you want your ABS to work correctly in cold weather. 

[MichiganBob]

Found it at Auto Zone. Neither O'Reilly or Advance Auto had it. It was marked down from $26 to $13. I'm considering going back and getting the other can for next time. I would not think that a couple of years shelf life would hurt it. 

[Randyjaco]

Buy only what you need to do the job plus a little to top up. Once that seal is broken, it will start to take on moisture and degrade.

[MikeB60]

Check the local Ford dealer.  DOT lV LV is the same spec found in the Motorcraft brake fluid. 

[LAF]

I use Bosch Dot 5.1  It is DOT 3 and 4 compatible.  I empty my brake system and use all new fluid on any flushes.  Use a baster to get the old fluid out and fill with fresh and start the bleed process.

 

Bosch Dot 5

[LAF]

21 hours ago, Randyjaco said:

Buy only what you need to do the job plus a little to top up. Once that seal is broken, it will start to take on moisture and degrade.

I have always questioned this.

 

If you open a can of brake fluid and use only half I have used the other half a month or two down the road with no issues.

 

My thought process is if my car has 3 year old brake fluid and I put 2 month old from a fresh open bottle it has to be better then what is in there. 

 

I did just that.  Used Bosch Dot 5.1 on my bike at the 24K, then used it 2 months later to flush my car brakes with new pads.  I also used it in my clutch in my car to clean that fluid. 

 

I mean you got cars on the road that have never had their brakes flushed in many many years.  IMHO 2 month sealed container brake fluid is better then used 3 year old fluid.  I use a piece of saran wrap over the threads and then put the lid on to help seal it but I have no hesitation using a open brake fluid container that I have had under my care since opening. 

 

While I agree you should buy what you need, it can be stored for a period of time and used after opening.  Especially using the newer DOT 5 Bosch Fluid.  DOT 5 lasts 100% longer then DOT 3 and 50% longer then DOT 4 and 10% longer for DOT 5.

[Paul De]

When Dot 5 first hit the market I used it in the brakes that specified Dot 3 because liked the idea of it not being hydroscopic like Dot 3 & 4 is.  I used plenty to flush out the old fluid.  Then I read that it could be a problem, but I never had an issue and eventually sold the bike to a friend who road it for years without having problems either.  He eventually sold it with all original components still working well.  With the complexity of the ABS systems on the RT I have been too chicken to make that switch and have stuck with what is specified, but wondered if Dot 5 could work. 

 

In any case, since then I have wondered that because Dot 5 is hydrophobic, does that mean any moisture will form a separate water phase somewhere in the system which might be even more corrosive where the water phase settles out?

[LAF]

8 hours ago, Paul De said:

When Dot 5 first hit the market I used it in the brakes that specified Dot 3 because liked the idea of not being hydroscopic like Dot 3 & 4 is.  I used plenty to flush out the old fluid.  Then I read that it could be a problem, but I never had an issue and eventually sold the bike to a friend who road it for years without having problems either.  He eventually sold it with all original components still working well.  With the complexity of the ABS systems on the RT I have been too chicken to make that switch and have stuck with what is specified, but wondered if Dot 5 could work. 

 

In any case, since then I have wondered that because Dot 5 is hydrophobic, does that mean any moisture will form a separate water phase somewhere in the system which might be even more corrosive where the water phase settles out?

Well there is where the every 2 year brake flush comes in.  I do it car and bike every 2 years. 

 

DOT 5.1 seems to have better stats then any DOT 3 or 4 I have seen.

 

I can tell you it works well on my 17.5 GS in the three flushes it has had.  Once at 1 year, and then every two years. 

 

Now one year for me was manufacture date not the date I bought it.

[MikeB60]

BMW specifically calls for DOT IV LV in the newer motorcycles, with the LV being low viscosity. The viscosity of LV vs regular DOT IV/V is almost half as low.  There are also lower viscosity DOT V fluids but I was unable to locate the specific viscosity of these fluids. I've got a driveway full of Fords with Bosch ABS pumps that also spec the DOT IV LV fluid. I'm not messing around with brake fluid specs, its DOT IV LV for me.  Here is a link with some info on LV brake fluid. LINK 

[MichiganBob]

Here is an interesting blurb from the NAPA webpage:

 

 

"When a bottle of brake fluid leaves the factory, it’s sealed so that it doesn’t come into contact with any outside air that might also contain moisture. Most brake fluid manufacturers state that a sealed bottle has no set expiration date. In a sense, the fluid doesn’t break down over time and offers the same level of performance even after years on the shelf.

An open bottle is a different story. Even if you’ve only poured a little out of the bottle, you’ve still introduced moisture into the equation, and the chemical process of absorbing that liquid from the air has begun. Most manufacturers recommend that any open bottle of DOT brake fluid should be used within 12 months, or else discarded. Keep in mind that a full year is the very outside limit of what would be acceptable. A three-month period is more likely to offer a better limit of safety in terms of keeping the boiling point near its original level.

OIL AND POWER STEERING FLUID

Engine oil follows a different guideline compared to brake fluid shelf life. Although moisture isn’t really an issue for oil, the lifespan of the additives packed inside the bottle has a definite impact on how long it can be stored before it should be thrown away. In a stable environment, where temperature doesn’t fluctuate dramatically or reach extremes of cold or heat, you can get about five years out of a bottle of motor oil. Check for an expiration date, as more manufacturers have started to add this to each container. Power steering fluid is a similar story. Unopened, three to five years under normal temperatures is a safe window for use."

[Paul De]

20 minutes ago, LAF said:

Well there is where the every 2 year brake flush comes in.  I do it car and bike every 2 years. 

 

DOT 5 seems to have better stats then any DOT 3 or 4 I have seen.

 

I can tell you it works well on my 17.5 GS in the three flushes it has had.  Once at 1 year, and then every two years. 

 

Now one year for me was manufacture date not the date I bought it.

I get you about doing the flush every two years for the BMW ABS systems, and yet here is the but.  With a hydroscopic brake fluid the moisture is suspended and is removed with a proper fluid change over.  If the brake fluid is hydrophobic, then there could be a chance the water phase sits in some nook or cranny of the system and isn't completely flushed out when the fluid is changed. Prolly overthinking this though.

[Hosstage]

I am a fan of flushing brake fluid on the bikes every 2 years. When I see the color of the old fluid, especially the rear brake, I know I've done the right thing. I think the rear just gets more abuse due to the heat.

 

[MichiganBob]

Interesting blurb from the Pentosin  web page:

 

"Low viscosity DOT4 brake fluid

Pentosin DOT 4 LV is a special brake fluid of highest DOT 4 performance levels and extremely low viscosity at cold temperatures. It offers safety against vapor lock; it has excellent resistance to absorbing and retaining water and provides superior corrosion resistance. Pentosin DOT 4 LV Brake Fluid is ideal for all modern vehicles with ESP and ABS. DOT 4 LV can be used in all vehicles that require DOT 4 fluid.

Product attributes:
- Appearance: Yellow & Clear - Density at 20°C: 1062 kg/m³ - Kinematic viscosity at 40°C: 6.4 mm²/s - Kinematic viscosity at -40°C: < 700 mm²/s - Melting point: >-50°C/ >-58°F - Flash point: >130°C/ >266°F - Ignition temperature: >200°C/ >392°F - Boiling point: >265°C/ >509°F - Wet boiling point: >170°C/ >338°F - pH Value: Slightly alkaline"

[taylor1]

22 minutes ago, MichiganBob said:

can be used in all vehicles that require DOT 4 fluid.

Interesting. I will be doing a flush on my1150rt this winter and will look into this more.

[PatM]

1 hour ago, LAF said:

I use Bosch Dot 5.  It is DOT 3 and 4 compatible.  I empty my brake system and use all new fluid on any flushes.  Use a baster to get the old fluid out and fill with fresh and start the bleed process.

 

Bosch Dot 5

I get from your link that you actually use DOT 5.1 not DOT 5.  It should be clear to all that DOT 5 isn't compatible with DOT 3 and 4. DOT 5.1 isn't a revision of DOT 5 and is fully compatible with DOT 3 and 4.

 

 

brake-fluid-15.webp

[Hosstage]

Great idea to name a product as a newer version of another but are not compatible in any way. That one always confused me, dot 5.1 has nothing to do with dot 5. Wtf?

[MichiganBob]

Rationality and logic are overrated and difficult to come by.

[dirtrider]

2 hours ago, LAF said:

I have always questioned this.

 

If you open a can of brake fluid and use only half I have used the other half a month or two down the road with no issues.

 

My thought process is if my car has 3 year old brake fluid and I put 2 month old from a fresh open bottle it has to be better then what is in there. 

 

I did just that.  Used Bosch Dot 5 on my bike at the 24K, then used it 2 months later to flush my car brakes with new pads.  I also used it in my clutch in my car to clean that fluid. 

 

I mean you got cars on the road that have never had their brakes flushed in many many years.  IMHO 2 month sealed container brake fluid is better then used 3 year old fluid.  I use a piece of saran wrap over the threads and then put the lid on to help seal it but I have no hesitation using a open brake fluid container that I have had under my care since opening. 

 

While I agree you should buy what you need, it can be stored for a period of time and used after opening.  Especially using the newer DOT 5 Bosch Fluid.  DOT 5 lasts 100% longer then DOT 3 and 50% longer then DOT 4 and 10% longer for DOT 5.1

Morning  LAF

 

If you DID use dot 5 (not 5.1) that can really screw your brake system up as 5.0 is silicone based. 

 

I have seen a number of vehicle brake systems that had long-term problems where dot 5 was used in a vehicle where dot 3 or 4 is specified.  Dot 5 is also way too thick to work properly in most ABS systems that were designed to use dot 3 or dot 4 (especially in cold weather),  this is even more of a problem if dot 5 is used in an ABS system designed to use dot 4 LV fluid. 

 

Hopefully you used the 5.1 & not the 5.0 but just forgot the .1 on the end. 

[Mike279]

The Bosch 5.1 rates well for all systems and systems that use Low Viscosity.  The can lists it is good for three years between changes. That is a nice bonus.  

[Paul De]

In my one case it was the silicone based Dot 5 on a mid 80’s Kawasaki.  While I didn’t experience any problems, there was plenty written that it could be a problem.  
 

I could be way off here but I suspect that Dot 5.1 vs Dot 4, has to a difference with max service temp/boiling point and maybe viscosity 

[LAF]

7 hours ago, PatM said:

I get from your link that you actually use DOT 5.1 not DOT 5.  It should be clear to all that DOT 5 isn't compatible with DOT 3 and 4. DOT 5.1 isn't a revision of DOT 5 and is fully compatible with DOT 3 and 4.

 

 

brake-fluid-15.webp 33.48 kB · 2 downloads

Sorry, it is DOT 5.1 and is NOT compatible with DOT 5

[LAF]

38 minutes ago, Paul De said:

In my one case it was the silicone based Dot 5 on a mid 80’s Kawasaki.  While I didn’t experience any problems, there was plenty written that it could be a problem.  
 

I could be way off here but I suspect that Dot 5.1 vs Dot 4, has to a difference with max service temp/boiling point and maybe viscosity 

-40 degrees for viscosity and 365 degree boiling point.

[LAF]

6 hours ago, dirtrider said:

Morning  LAF

 

If you DID use dot 5 (not 5.1) that can really screw your brake system up as 5.0 is silicone based. 

 

I have seen a number of vehicle brake systems that had long-term problems where dot 5 was used in a vehicle where dot 3 or 4 is specified.  Dot 5 is also way too thick to work properly in most ABS systems that were designed to use dot 3 or dot 4 (especially in cold weather),  this is even more of a problem if dot 5 is used in an ABS system designed to use dot 4 LV fluid. 

 

Hopefully you used the 5.1 & not the 5.0 but just forgot the .1 on the end. 

Thank you for correcting a typo that could be a real issue. 

 

I used the above Bosch 5.1 and it is NOT compatible with ANY 5.0 DOT system as you mention.

 

I like Bosch products and think the DOT 5.1 to be superior to any other DOT 5.1.  Of course that is my opinion, and as with oil, whatever flavor you like is good, just change it.

 

 

[Mike279]

That 365 is wet boiling point as in contaminated with moisture.  520 is the dry boiling point.  Yup I am a fan too.

[Dave_in_TX]

I am also a DOT 5.1 user. The viscosity is similar to low viscosity DOT 4 and has a higher boiling point.

[Paul De]

I think if I lived in the mountains or was using the bike for track days, where your brakes would be used for long period or frequent heavy braking, I'd consider switching from Dot 4 to Dot 5.1.  I doubt that most Wethead riders are subjecting their brakes to that kind of use though. I sure am no where near using my brakes that hard to worry about brake fluid boiling points.  Haha, as I gotten older and my testosterone level has tapered off I'm more often trying to perfect smooth and quick when riding frisky. 

 

Anyway, I think this is bit like the best engine oil to use thing and in any case use what meets the manufacturers specification, but while under warranty use the specific stuff specified in the manual to avoid giving the manufacturer a way to weasel out of covering a defect.

[6speedTi]

[dirtrider]

47 minutes ago, 6speedTi said:

 

Afternoon 6speedTi

 

That chart is kind of outdated as it doesn't include the newer Dot 4+ or dot 4 LV (Low Viscosity) that the newer BMW motorcycles are specified to use.   

[6speedTi]

1 hour ago, dirtrider said:

 

Afternoon 6speedTi

 

That chart is kind of outdated as it doesn't include the newer Dot 4+ or dot 4 LV (Low Viscosity) that the newer BMW motorcycles are specified to use.   

Yes I'm sure but the biggest misconception is the DOT 5 and DOT 5.1 fluids. They are not compatible but it is confusing if one does not pay attention. My 2012 RT calls for Dot 4. I've heard people say you can or should use DOT 4 LV instead. I would guess that either is suffice since the manual called for DOT 4 way back when I purchased the CD manual. I've used DOT 5.1 in the past on a brake bleed/flush servicing. Differences are the wet and dry boiling points. I've been using Pentosin Dot 4 now on all my vehicles. Good product and approved by many European vehicle manufacturers. If the LV is better then I'll switch over to Pentosin DOT 4 LV in the future. 

Thanks for the information. 

[dirtrider]

38 minutes ago, 6speedTi said:

Yes I'm sure but the biggest misconception is the DOT 5 and DOT 5.1 fluids. They are not compatible but it is confusing if one does not pay attention. My 2012 RT calls for Dot 4. I've heard people say you can or should use DOT 4 LV instead. I would guess that either is suffice since the manual called for DOT 4 way back when I purchased the CD manual. I've used DOT 5.1 in the past on a brake bleed/flush servicing. Differences are the wet and dry boiling points. I've been using Pentosin Dot 4 now on all my vehicles. Good product and approved by many European vehicle manufacturers. If the LV is better then I'll switch over to Pentosin DOT 4 LV in the future. 

Thanks for the information. 

Evening  

 

The camhead is kind of a tossup, my late BMW parts book shows " BRAKE FLUID DOT4 LV, LOW VISCOSITY" for the camhead but I would be willing to bet that your master cylinder covers says USE DOT 4. 

[Dave_in_TX]

On 10/5/2022 at 9:50 AM, Paul De said:

I think if I lived in the mountains or was using the bike for track days, where your brakes would be used for long period or frequent heavy braking, I'd consider switching from Dot 4 to Dot 5.1.  I doubt that most Wethead riders are subjecting their brakes to that kind of use though. I sure am no where near using my brakes that hard to worry about brake fluid boiling points.  Haha, as I gotten older and my testosterone level has tapered off I'm more often trying to perfect smooth and quick when riding frisky. 

 

Anyway, I think this is bit like the best engine oil to use thing and in any case use what meets the manufacturers specification, but while under warranty use the specific stuff specified in the manual to avoid giving the manufacturer a way to weasel out of covering a defect.

In the past, DOT 5.1 was easier to obtain than DOT 4 LV. The two don't appear to much different in price.

[6speedTi]

6 hours ago, dirtrider said:

Evening  

 

The camhead is kind of a tossup, my late BMW parts book shows " BRAKE FLUID DOT4 LV, LOW VISCOSITY" for the camhead but I would be willing to bet that your master cylinder covers says USE DOT 4. 

I'll never play poker with you. I wonder if the later Camheads  specify otherwise? 

[nh1200c]

I think that BMW has (relatively) recently moved to DOT 4 LV as the maintenance section of the owner's manual (as recently as 2021) for the RT still shows DOT 4. Additionally, the Repair DVD (for the 2020 RT) still shows DOT4 as the required fluid for brake flushes and service. 

The only reference I can find to DOT4 LV is the fact that MaxBMW shows DOT4 LV in their maintenance items for the bike. 

 

D.R. - do you have a reference for a service bulletin or letter concerning the LV brake fluid? Just looking to find the source of this and nail down its applicability. 

 

Ride safe - 

Larry

[dirtrider]

50 minutes ago, nh1200c said:

I think that BMW has (relatively) recently moved to DOT 4 LV as the maintenance section of the owner's manual (as recently as 2021) for the RT still shows DOT 4. Additionally, the Repair DVD (for the 2020 RT) still shows DOT4 as the required fluid for brake flushes and service. 

The only reference I can find to DOT4 LV is the fact that MaxBMW shows DOT4 LV in their maintenance items for the bike. 

 

D.R. - do you have a reference for a service bulletin or letter concerning the LV brake fluid? Just looking to find the source of this and nail down its applicability. 

 

Ride safe - 

Larry

Morning Larry

 

I don't have anything from BMW on using Dot 4 lv in a Dot 4 system (there might be something but I haven't seen anything myself) . From some of the brake performance testing I have seen at the motor company I work for indicates using Dot 4 lv in a Dot 4 system causes no big braking issues. But going the other way (using Dot 4 in a Dot 4 lv system) can cause some issues in very cold ambient temps with the stability control response. 

 

Personally, I just go with what is on the master cylinder cap as that is what the motorcycle came with & more importantly what the ABS system was originally calibrated with. 

[nh1200c]

3 hours ago, dirtrider said:

Morning Larry

 

I don't have anything from BMW on using Dot 4 lv in a Dot 4 system (there might be something but I haven't seen anything myself) . From some of the brake performance testing I have seen at the motor company I work for indicates using Dot 4 lv in a Dot 4 system causes no big braking issues. But going the other way (using Dot 4 in a Dot 4 lv system) can cause some issues in very cold ambient temps with the stability control response. 

 

Personally, I just go with what is on the master cylinder cap as that is what the motorcycle came with & more importantly what the ABS system was originally calibrated with. 

I agree completely with that approach, specifically the DOT4 was what the ABS system was calibrated with! 

 

Have a great weekend,

 

Larry

[Twisties]

On 10/4/2022 at 7:39 AM, MikeB60 said:

BMW specifically calls for DOT IV LV in the newer motorcycles, with the LV being low viscosity. The viscosity of LV vs regular DOT IV/V is almost half as low.  There are also lower viscosity DOT V fluids but I was unable to locate the specific viscosity of these fluids. I've got a driveway full of Fords with Bosch ABS pumps that also spec the DOT IV LV fluid. I'm not messing around with brake fluid specs, its DOT IV LV for me.  Here is a link with some info on LV brake fluid. LINK 

My 2020 and Sharon's 2021 R 1250 GS's specify DOT 4.  

[Boxflyer]

Specifications for vehicles are constantly changing...go with what is the current Manufacturers recommendation.

 

Here are the BMW vehicles that are now supposed to be using DOT4 LV.

Don't go wandering all over the internet looking for something new and exotic just to be a "test Pilot".

 

This has been beat to death!

 

 

 

[Skywagon]